Method and apparatus for preventing offset in printing



'.Aug. 23, 1932.

,T. E. KNOWLTON AND APPARATUS FOR PREVENTING OFFSET IN Filed July 20, 1931 1mm modorefiz vzowlzbm Patented Aug. 23, 1932 UNITED STATES 'rnnonoan E. kuow xron, or NEW YORK, N. Y.

METHODIAND ArrARATus ron rammme orrsn'r m rnmrme Application filed July 20,

This invention pertains to a method and apparatus for printing, whereby both sides of a blank sheet may be printed with characters, marks, colors or symbols in clear distinct outlines without any smearing or blurring resulting on the previously printed side. It relates particularly to the facing of the impression or tympan cylinder or cylinders with a novel and improved printing blanket for supporting the blanks to be printed.

The invention consists in the novel methods, combinations and arrangements hereinafter described for carrying out the abovestated object and such other objects as will hereinafter appear.

This invention may be understood readily by reference to exemplifications thereof described in the following specification. In

such exemplifications, a blank to be printed,

for example paper, is fed through any type of printing apparatus having one of the tympan cylinders provided with a. forami- 'nated facing layer of finely meshed metal screening and a granular surfaced sheet interposed between the metal facing sheet and the tympan cylinder with the granular faced side of the interposed sheet in contact with facing screen. Illustration has been made only of that part of the printing apparatus which is utilized to carry the present invention into effect.

In the drawing:

Fig. 1 is a view in central vertical sectional elevation of that part of a printing apparatus embodying my invention;

Fig. 2 is a similar view of another modification; and

Fig. 3 is a similar view of still another modification.

Referring to the drawing, numeral 1 designates a blank sheet which is fed from any source of supply, as from reel A, through a printing apparatus and then cut in pieces, wound upon reel B, or otherwise disposed of after it has been printed. The sheet is printed on both sides by feeding same in contact with a series of printing rolls disposed to print first on one side and then on the reverse side of the blank. In the illustrated constructions, a series of printing cylinders 1931. Serial 1T0. 551,917.

tympan cylinder cooperating with the printing cylinder 2 to support the blank while the printed matter is being imparted thereto, and numeral 6 typifies an inking device for the printing cylinders. While I have shown the printing cylinders to be horizontally dis- 5 posed, it will be understood that this is merely one illustration. They may be vertically disposed or arranged in any other desired manner to print alternately on first one side and-then on the other side of the blank with- .5

out departing from the spirit of the invention.

Printing cylinder 3 of the second series of prlnting cylinders is similar to printing cylinder 2, and is likewise provided with an to inking device represented at 7. However, after the blank has been printed on one side and is then printed on the reverse side before the ink has dried, care must be taken to avoid smearing or blurring on the.printed side. It

has been customary heretofore to run an offset sheet of ink-repellent material over the tympan cylinder 5 while the reverse side is being printed to avoid destruction of or injury to the first printing side, but this has 0 met with only partial success. Even though the offset sheet be of a special and superior grade of material, it will not revent blurrin of the outlines or avoid pic ing-up-the infi from the sheet while in contact with the blank. Because it does take on ink from the printed sheet, the offset sheet, is unfit for continuous use without imminent da er of injury to the printed matter on the lank.

I discovered that smearing or blurring of the printed side could be avoided by providing an offset sheet or roll of special construction or surfacing a conventional tympan cylinder with a roughened covering such as emery or sandpaper, or the like, all of which is described and claimed in Patent No. 1,731,464, issued to me on October 15, 1929. As is clearly described in my patent, a partly printed sheet may be supported on an emery or sandpaper covering with the printed side in contact therewith while it is being printed on the reverse side. A sheet so supported while being printed on the reverse side will not mar or blur the already printed side nor absorb any ink therefrom.

The present invention is an improvement upon the patented construction and pertains to'a construction in which a roughened sheet 8, such as emery or sandpaper, is used to face the tympan roll 5 either by being placed directly thereon or over a conventional printing blanket 9 of fabric or some resilient material, for supporting a foraminated covering 10, typified by a 100 to 500 mesh screen cloth.

The use of a metal screening sheet as the top facing of a tympan cylinder is productive of good printing, but due to the great stress to which the top sheet is subjected on a fast running press, there is a tendency for the strands to stretch unless the screen is con structed of expensive and high grade steel or alloyed wire. When the strands stretch under the stress of the rolls or printing, the screening becomes wavy and bunches up in spots, causing it to break at these points. This objectionable feature, however, is prevented if the screening is supported on a sanded sheet. Apparently, the sanded sheet provides more uniform support and distributes the stress evenly over all parts ofthe strands. Accordingly, cheaper and inferior grades of screening may be employed to the same advantage as the superior grades, and

irregular stretching of the strands is overcome.

The foraminated sheet 10 may be tightly clamped over the face of the tympan cylinder in any well-known manner (Fig. 1) or may be in the form of anendless belt 11 (Fig. 2) circumvolved over tympan cylinder 5 and one or more idlers l2 and 13. In the modification of Fig. 3 the foraminated sheet is in the form of a strip 14 adapted to be traversed from a feed roll 15 over tympan roll 5 to a winding roll 16, after which it may be used over and over again.

Obviously the invention is not restricted to the particular eimoodiinents herein shown and described, neither is it necessary that all features of the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations. 1

I claim:

1. A method of preventing offset in printing characterized by printing a blank sheet ."upon one face, supporting the sheet on a foraminated layer, and supporting the foraminated layer on an irregularly surfaced layer, and then printing the sheet on" the reverse side.

2. A method of preventing offset in printing characterized by printing a blank sheet upon one face, supporting the sheet on a foraminated layer, supporting the forami- 'nated layer on a granular surfaced layer,

' side of the sheet.

4. A method of concomitantly printing a blank sheet on opposite faces comprising feeding one face of a sheet in contact with a printing roll, traversing a flexible foraminated support with the sheet, supporting said flexible foraminated support on a granu lar surfaced sheet, and printing the reverse face of the sheet while on said foraminated support.

5. A method of preventing offset in print ing a blank sheet on opposite faces comprising printing one face of the sheet, supporting the sheet on the printed side over a forami- 'nated surface, supporting the foraminated surface on a granular surfaced sheet, and simultaneously printing the reverse face of the blank.

6. The method of preventing offset in printing a blank sheet on opposite faces comprising first printing one face of the sheet, traversing the sheet in contact with alayer of screenlng, supporting the layer of screening on a granular surfaced layer, and simultaneously printing the reverse face of the blank.

7. The method of successively printing opposite faces of a continuously traversing sheet, supporting said sheet on a layer of screening to receive the subsequent print, and supporting the layer of screening on a granular surface layer.

8. A method of preventing ofiset in printing characterized by printing a blank upon one face, supporting said blank on a platen with the printed side in contact with a finely meshed metal layer of screening, supporting said layer of screening on a granular surfaced layer, and printing the reverse side while in contact with the layer of screening.

9. Printing apparatus comprising a series of printing rolls disposed to print on opposite faces of a sheet, tympan rolls cooperating with the printing rolls, a foraminated layer cooperating with the printing roll which prints the reverse face of the sheet, and a granular surfaced layer supporting the foraminated layer.

10. Printing apparatus comprising a series of printing'elements disposed to print alternately on opposite faces of a sheet, supporting means cooperatin with the printing elements, a foraminate layer associated with the subsequent supporting means to prevent dispersion of the ink on the initially printed face, and a granular surfaced sheet for supporting the foraminated layer.

11. In a printing apparatus of the character described, means for successively printing on opposite sides of a continuously traversing sheet, a screening layer for supporting the sheet subsequent to the initial printing, and agranular surfaced sheet for supporting the screening layer.

12. In a printing apparatus of the character described, a printing and tympan roll for printing one face of a sheet, a printing and tympan roll disposed to print the reverse side of the sheet, a foraminated layer traversing with the second tympan roll to contact with the printed face of the sheet, and a granular surfaced sheet supporting said foraminated layer.

13. In a printing apparatus of the charac-- ter described, means for printing one face of a traversing sheet, means for printing the reverse face of the sheet, a screen faced offset roll cooperating with the second printing means, and a granular surfaced support for the screen facing on the offset roll.

14. A printing apparatus of the character described comprising a printing device, a platen associated with the printing device, means faced with a screening layer cooperating with the platen to support a printed blank, and a granular surfaced layer supporting-the screening layer.

15. A printing apparatus comprising a printing device, a platen associated with the printing device, a facing for the platen including a flexible metal layer to support a printed blank, and a granular surfaced layer for supporting the flexible metal layer.

16. A platen'means for a printing apparatus having a foraminated layer on which a. printed sheet is adapted to be'supported and a granular surfaced layer for supporting the foraminated layer.

17. Printing apparatus comprising a seposed sheets, including a finely meshed metal screening, and a granular surfaced layer on which said metal screening is supported as 11. facing layer.

Signed at New York city, 1n the county of New York and State of New York, this 11th day of July, 1931.

THEODORE E. KNOWLTON.

ries of printing rolls disposed to print on opposite faces of a blank, tympan rolls cooperating with the printing rolls, a facing of finely meshed metal screening surrounding.

the tympan roll which supports the blank wlnle being printed on the reverse side, and

a granular surfaced layer for supporting the metal screening facing.

18. A platen means for a printing apparatus having a facing of finely meshed metal screening on which a printed sheet is adapted to be supported, and a granular surfaced sheet for supporting the metal facing.

19. A printing blanket consisting bf a finely meshed metal screening and a granular surfaced sheet.

20. A printing blanket comprising super- 

